The present invention relates to a sheet feeding device for feeding recording sheets to a copier or the like.
A sheet feeding device of a certain type includes a restricting section, a displacement section, and a link section and identifies the size of a recording sheet placed on a sheet support (see Japanese Patent Laid-Open Publication No. HEI 11-139572). The restricting section restricts the position of the recording sheet placed on the sheet support by abutting against an edge of the recording sheet. The link section interlinks the restricting section and the displacement section to displace the displacement section in accordance with a sliding movement of the restricting section. The position of the displacement section is detected by a sensor.
Japan and European countries generally adopt ISO•JIS as industrial standards for recording sheets, while North American countries generally adopt International Standards. Sizes of recording sheets conforming to ISO•JIS include A4 size and B5 size. Sizes of recording sheets conforming to International Standards include letter size and legal size. A4 size is 210×297 mm. B5 size is 182×257 mm. Letter size is 215.9×279.4 mm. Legal size is 215.9×355.6 mm.
A standard sheet of A4 size (hereinafter will be referred to as “A4 sheet”), a standard sheet of letter size (hereinafter will be referred to as “letter sheet”) and a standard sheet of B5 size (hereinafter will be referred to as “B5 sheet”) have their respective long side dimensions which are approximate to each other. The difference in long side dimension between A4 sheet and letter sheet is smaller than the difference in long side dimension between letter sheet and B5 sheet. For this reason, a sheet feeding device meeting both of ISO•JIS and International Standards is likely to cause an error in identifying the sizes of A4 sheet and letter sheet. If the linkage between the displacement section and the restricting section is highly precise and, at the same time, the resolution of the sensor is high, the sheet feeding device mentioned above can realize size identification with high precision. However, some levels of dimensional precision of each of the restricting section, gear member and displacement section make it difficult to link the position of the displacement section to that of the restricting section.
A feature of the present invention is to provide a sheet feeding device capable of identifying the sizes of standard sheets with high precision irrespective of the level of dimensional precision of each of the restricting section, gear member and displacement section.